MCS Certificate & Structural Calculations - Solar & Battery installation

Solar and battery installations (if done together as part of the same installation) are currently at 0%. However, our company is MCS accredited and we issue MCS certificate once work is complete for which 20% VAT is charged. We also do structural calculations which is mostly done in-house. However, occasionally, it is done through MCS. Again, this is currently being charged to customer at 20% VAT. Our thinking is that these are professional services and won't come under the 0% remit. However, the energy grant companies disagree. Should these be charged to customer at 0% as they are required as part of the installation?

Hi Suzanne Lyon,
The VAT relief for energy saving materials would only include the supply and installation of energy saving goods in to residential buildings and would not include the supply of professional services.
Please see the guidance below:
Energy-saving materials and heating equipment (VAT Notice 708/6)
Thank you.